Method and apparatus for cleaning strip material



Oct 1963 R. P. GUTTERMAN 3,

METHOD AND APPARATUS FOR CLEANING STRIP MATERIAL Filed Nov. 50, 1961 N 2 Sheets-Sheet 1 INV EN TOR. MM

1963 R. P. GUTTERMAN 3,

METHOD AND APPARATUS FOR CLEANING STRIP MATERIAL I Filed Nov. 30, 1961 2 Sheets-Sheet 2 INVENTOR. Zf H V I 22 e; fi fiffmg m MAW, M rm United States Patent This application relates to an improvement in cleaning devices and methods and specifically is directed to a novel and improved cleaning device particularly adapted for cleaning elongated or strip objects such as tapes, ribbons or extrusions of metal or plastic material, hereinafter generally termed strip materia The increasingly prevalent use of magnetic tape for sound recordings and computer use has especially created a problem which has existed for some time in the cleaning of the magnetic tape material. If such tape material is dirty, i.e., having a surface bearing foreign particles or greases and oils, regardless of the quality of the record, the transcription thereof will lack accuracy and fidelity. In computer work, it is extremely important that the tape be of maximum cleanliness possible.

In addition to magnetic tape, many other articles are used which may be designated as elongated or strip objects within the contemplation of this invention. For instance, metallic wire is also used in applications where its cleanliness is of great importance, and relatively long and slender metal extrusions of variously complicated cross sections are produced and these also are frequently desired with a clean surface. Another example of strip material is photographic film, particularly motion picture photographic film, whether 8, 16 or 35 mm. or other width (such film also being used for still photography). The cleaning of photographic film is of vital importance to prevent damage to the image containing emulsion thereon. As with magnetic tape, photographic film does not have a particularly hard surface, and it is accordingly necessary that the cleaning technique employed be such that surface scratching does not occur, since the scratches can lead to just as severe, it not more severe, disadvantages as the presence of dirt, grease, oil, etc.

The device and method provided by the present invention is particularly adapted for the cleaning of such elongated or strip objects, in a rapid, inexpensive and safe fashion.

It is, therefore, an object of this invention to provide a method for the cleaning of strip materials having, generally, a longitudinal dimension which is very large in comparison to the transverse dimensions. It is also an object of this invention to provide a device suitable for the operation of said method. More specifically, it is the object of this invention to provide a method of cleaning for elongated or strip objects, in a suitable fluid by causing a rapid flow of the latter along said strip material, while causing at regions of said flow very substantial changes in the rate of flow and consequently changes in pressure suflicient to cause cavitation in the fluid.

A further object of this invention is to provide a device for cleaning strip material including walls defining a chamber having a central portion and outlets relatively narrow and constricted with respect to said central portion, means for delivering a liquid to said central portion of said chamber and for flowing said liquid out of said chamber through said outlets at a'velocity whereby cavitation is caused in the region of said outlets, and means inducing relative motion between said strip material and said outlets, first counter-currently and then cocurrently with respect to the liquid flow from said respective outlets.

Further objects of this invention include the provision 3,1fi8dl25 Patented Oct. 22, 1963 ice of suitable transporting devices for appropriate control of the spacing of said outlets, and control of the device and maintenance of the conditions therein. Other ob jects will be apparent from the following description of the invention.

In the drawings:

FIGURE 1 is a perspective view of the cleaning device showing one form of arrangement in a tank for the cleaning liquid;

FIGURE 2 is a schematic view of one form of the overall system for the cleaning device and method of this invention;

FIGURE 3 is a plan view of one form of the cleaning device provided by this invention;

FIGURE 4 is a side elevational view of the cleaning device of FIGURE 1, partly in section; and

FIGURE 5 is a sectional view of the cleaning device taken along the lines 5-5 of FIGURE 4.

Referring to the drawings, the cleaner provided by this invention is designated, generally, as 8 and has, as indicated, an upper assembly 10 and a lower assembly 11. Between the said upper and lower assemblies, there is formed a chamber 12 having outlets 14 and 15. The cleaner, as illustrated, is arranged for the cleaning of magnetic tape 16, which is delivered and carried on a path through the chamber 12 guided by two pairs of guide rollers, 18, 20 and 19, 21, as shown in FIGURES 1 and 2.

As shown, the upper and lower assemblies 10, 11 will generally be identical in construction so that the chamber 12 defined therebetween is symmetrical in vertical cross section. Accordingly, a description of the upper assembly 10 will also serve to describe the lower assembly 11, but when necessary for clarity, elements of the lower assembly will be designated by the corresponding numeral used in the upper assembly followed by the letter a.

The upper assembly 10, as shown, comprises generally parallel side walls 22, 22 spaced apart from each other and respectively abutting the side edges of the profile plates 24, 26. These profile plates 24, 26 are in turn clamped along their portions 28, 30 between lower clamp blocks 32, 3-4 and upper clamp block 36, with gasket 37, by means of machine screws 38. Bolts 41 secure side walls 22, 22 in position as shown.

Upper clamp block 36 is adapted to receive in liquid tight sealing relationship therewith a pipe 40, in open communication with the chamber 12. Gasket 37 maintains a fluid-tight seal at the upper boundaries of chamber 12.

Adjustment of eccentric cams 42, 44 and their counterparts, in the lower assembly 11, permit control of the spacing between profile plates 24, 24a at outlet 14 and of the spacing between profile plates 26, 26a at outlet 15, and particularly the spacing 50, best seen in FIGURE 5.

Since profile plates 24, 26 will resiliently flex inwardly and outwardly in response to adjustment of earns 42, 44, such adjustment will generally control the crosssectional profile of the chamber 12 and the outlets 14, 15, and therefore the performance characteristics of the cleaning device of this invention, subject of course to control of and adjustment of other conditions, as will be described hereinafter.

Arranged outwardly of outlets 14, 15 are deflector plates 46, 45. These are mounted on the ends of side walls 22, 22' spaced somewhat from the end of the profile plates 24, 26. The generally upwardly curving deflector plates 46, 48 terminate substantially short of abutment with the edges of clamp blocks 32, 34, 36.

Pipes 40, 40a are each connected to a suitable pumping assembly schematically shown as 52 in FIGURE 2, and a filter 54 for delivery of the cleaning liquid to chamber 12 at high rates, and for forcing the same to exit from chamber 12 through outlets 14, 15, at high velocities. It will be seen that because of the cross-sectional profile of chamber 12, under these conditions of forced fluid flow the gradual restriction approaching the region 50 of outlets 14, 15 will cause, in accordance with the principle of the well-known Bernoulli effect, a decrease in the pressure on the more rapidly flowing liquid. At some region, generally observed at about 56 (see FIGURES 1 and 4) vapor bubbles will begin to appear in the liquid, due to the hydrostatic pressure dropping to a level of about or below the vapor presure of the liquid itself. These bubbles are carried with the stream of fluid as it exits through outlets 14, 15 and into the regions 58 (see FIGURES 1 and 4). Here the profile plate constrictions on the fluid flow are somewhat abruptly removed and the velocity of fluid flow through the orifice of the outlets 14, 15 decreases with corresponding increase in hydrostatic pressure. Partially through the design of deflector plates 46, 48, there is thus reimposed on the flowing fluid pressures in excess of the fluid vapor pressure, and this pressure increase causes an implosive collapse of the bubbles.

The phenomena occurring at and between regions 56, 58 are essentially fluid cavitation phenomena with the imposition of high stress forces on any relatively solid surfaces therein. The bombardment and high energy release which occurs in this cavitation region has the effect of dislodging and physically removing foreign particles from the surface of the flexible strip material, such as magnetic tape 16, as it passes through the outlets 14, 15. Perhaps due to the extreme agitation resulting from the cavitation phenomenon, oils and greases also appear to be removed by solution or the formation of at least a transient emulsion in the cleaning fluid and this foreign matter is carried away in the fluid flow.

Completion of the cleaning of the strip material is then achieved by removing the same from the liquid bath, with suitable drying thereof, as desired.

The overall arrangement of the cleaner system and apparatus of the present invention is best seen from FIG- URES 1 and 2. As shown, the cleaning device 8 is positioned in a tank 60, with lower assembly 11 being mounted on the bottom of the tank by machine screws 33a (FIG. 4) extending into clamping blocks 32a, 34a and 36a, being also arranged with gasket member 62. Pipe 40a extends to the bottom of the tank and is connected in turn through pipe or hose 64 to the pump 52. The pipe 40 on the upper assembly is equipped with a sealing disc 66 which is adapted to abut against the side wall of the tank 60 in liquid tight relationship with a suitable conventional fixture also connected to pipe or conduit 68 which leads in turn to pump 52. As can be seen from FIGURE 2, operation of pump 52 will deliver the cleaning fluid or liquid through conduits 64, 68 and 40a, 40 and thence to the chamber 12 of the cleaner.

The liquid level in tank 60 will generally be maintained above the sealing member 66, so that the entire cleaning device 8 is well immersed therein. This level may be suitably maintained by a conventional standpipe 160. Drainage from the tank is arranged via line or conduit 70 to a suitable filter 54, see FIGURE 2, for re-circulation to pump 52 after solids have been filtered from the recycled liquid.

It will be appreciated that but for deflector plates 46, 48, the high velocity liquid flowing out of chamber 12 through outlets 14 and 15, would generate turbulent waves against the side walls of tank 60, and would lead to a splashing problem. Deflector plates 46, 48 serves to direct a major portion of the liquid flow back to the middle of the tank, rather than against the in-walls, the liquid flowing from the two ends of the cleaner impinging against itself to substantially nullify and depress undue turbulent waves, and splashing. This re-direction of liquid flow by deflector plates 46, 48 also serves to remove the liquid rapidly from the region immediately outside of outlets 14, thereby cooperating to eliminate a back 4.- pressure resistance to liquid flow through the orifice of outlets 14, 15, which permits more eflicient operation of the device.

As shown in FIGURES l and 2, the flexible strip material or magnetic tape 16 may be delivered from the supply reel 72 and then over and around guide rollers 19, 21, 20 and 18, in that order, and then on to take-up reel 74. Guide rollers 18 and 19 may be mounted on the sides of the tank 60' as shown, but for ease of operation it is preferred to have guide rollers 20 and 21 mounted on a vertical track so that they can he raised out of the tank to a height at least slightly above guide rollers 18 and 19. This will permit threading of the strip material 16 directly across the top of the tank and onto guide rollers 18 and 19, and thereafter guide rollers 20 and 21 can be lowered, thereby lowering the strip material 16 into the tank and into position for cleaning.

A suitable track of this sort is schematically shown in FIGURE 1 with vertical channel track 76 carrying wheel 78 mounted on the shaft 8! of the guide roller 21. Attached to the shaft 86 is a chain or cord 82, which is, as shown, arranged with a suitable pulley and take-up device 86. A similar arrangement, not shown, is also provided for guide roller 20, and by these means guide rollers 26 and 21 can be raised or lowered as desired.

As also shown in FIGURE 1, upper assembly 10 is suitably mounted so that it can be pivoted out of the vertical plane of the path of the tape along lower assembly 11, and when the cleaner is to be loaded with flexible strip material, the cleaner is opened in this fashion. As schematically shown in part in FIGURE 1, upper assembly 10 may be suitably pivoted on a conventional over-center toggle linkage 88 the arms thereof *being pivoted on roll pins 6, 92 in the upper clamping block 36. Conveniently, the over-center toggle linkage is arranged so that when closed the polished metal edges 94a, 96a of side Walls of upper and lower assemblies 10, 11 are formed into a tight metal-metal seal, while at the same time member 66 is forced into sealing engagement with the side wall of tank 60.

In operation for cleaning a flexible strip material the cleaner in the tank 60 is first placed in the open position as shown in FIGURE 1 and the strip material is threaded across guide rollers 18, 19. Guide rollers 20, 21 are then lowered into the tank, carrying the strip 16 down with them and placing it along the top of lower assembly 11 and between and parallel to the edges of side walls 22a, 22a. The upper assembly 10 may then be pivoted into the operating position shown in FIGURES 2 and 4, and with the sealing member 66 engaging the mating fixture on the side wall of tank 60. At this point pump 52 may be turned on and the cleaning liquid will be delivered to chamber 12 through pipes 40, 40a. Preferably, approximately equal flow rates into chamber 12 are maintained through each of pipes 40, 40a to ensure that the strip material 16 is balancedly supported and travels through the chamber and outlets 14, 15 without substantially touching any portions of cleaning device 8. This will prevent physical damage to the strip material. Preferably, the outlets 14, 15 should be of equal cross section to balance the fluid friction forces exerted by the fluid on the strip material 16. This, in turn, exerts a slight stretching tension on the strip material 16 in chamber 12, tending to further stabilize the positions of strip material 16 out of contact with the structure of the cleaning device 8.

The pumping volume and pressure is maintained such that the liquid must be expelled from chamber 12 through outlets 14, 15 at a high velocity sufficient to produce the cavitation effect previously referred to. It has been found important to simultaneously move the tape 16 through cleaner at relatively high rates of speed for the cavitation energies are of such magnitude that damage can be done to the coating thereon if the tape is stationary for even a few seconds.

It will be seen that the tape moves longitudinally through the cleaner first passing in through outlet 15 into chamber 12 and then out through outlet 14. The tape thus travels in a direction counter-current to the liquid flow at a first region of cavitation and then cocurrent with the liquid flow at a second region of cavitation. This is advantageous since the surface irregularity of somemagnetic tapes is longitudinally asymmetrically oriented, and adequate cleaning is achieved only by the liquid flow in each direction.

It is believed clear from the above discussion that the most important operating feature of applicants invention is the arrangement of a suitably shaped chamber 12 in conjunction with a selection of operating conditions of pumping volume and temperature, in conjunction with the cleaning liquid selected, such that cavitation will occur in the regions 56, 58. Since the cavitation phenomenon primarily results from more or less abrupt changes in pressure in the regions 56, 58, the external or atmospheric pressure on the cleaning liquid is also, of course, a significant process variable. However, because the device will generally be operated at ambient atmospheric pressure, in practice no special control of the pressure on the liquid in tank 69 is required. If there are wide fluctuations in the existing atmospheric pressure at the place where the cleaning equipment is operated, minor adjustment of cams 42, 44 will adjust the spacing 50 to provide the proper pressure changes over the region 55, 58, so that adequate cavitation continues to take place.

A more significant operating condition for control is the temperature of the cleaning liquid, since the vapor pressure thereof will vary with temperature. Variation in vapor pressure will, of course, alter the performance of the cleaning device of this invention unless the spacing at outlets 14, 15 is suitably adjusted to accommodate the same. When there is an increase in temperature, with an increase in vapor pressure of the cleaning liquid, space 50 can be made larger since the hydrostatic pressure will fall below the vapor pressure at lower velocities of liquid flow.

In any case, however, it is a simple matter to adjust the spacing 50 for any given set of conditions of pressure, temperature, and cleaning liquid to achieve optimum cleaning performance of the device.

Any conventional cleaning liquid may be employed in the practice of this invention, however, it is preferred to use an aqueous medium since this is the easiest to handle. With some strip materials, such as photographic film, it is desirable to use on organic liquid such as Freon or methyl chloroform. Various additives may be introduced into an aqueous bath such as small quantities of detergents, alcohol, or mineral or emulsified silicone oils. The use of the latter is especially helpful in the cleaning of metallic computer tapes, since the tape will be coated with a thin film of the oil as it exits from tank 69, and this will provide protection against rust. It has been observed in the practice of this invention that unless this precaution is taken, the cleaning efl'iciency of the device of the present invention is so great that the protective and highly adherent silicone oil coating originally placed on such metallic tapes by the manufacturer to prevent rust is actually itself removed in the cleaning operation.

As an example of the practice of the present invention, devices of the form illustrated in FIGURES l-5 have been employed for cleaning one-half inch wide magnetic tape. Wherein the cams 42, 44 are spaced some 7 inches apart, the maximum height of the side walls 22, 22 is about of an inch and the side walls 22, 22' are approximately 1% inches high. Using the device of such size, a half inch magnetic tape may be effectively cleaned while traveling through the device at a rate of 309 ft. per minute. At normal room temperatures and pressure, a pumping volume of 5 gallons per minute is adaquate to induce cavitation for this cleaning efficiency. Tens of thousands of feet of magnetic tape have been 6 cleaned in this fashion and the cleaning efiiciency in performance of the device is constantly maintained at the same high level, as might be expected from its simplicity in construction and substantial freedom from moving par-ts other than the pump.

It is a feature of the construction of the cleaning device as shown in FIGURES 1-5 that the profile plates 24, 24, 26, 26 are easily replaced. This is an advantage because over an extended period of use, the intense cavitation which takes place at outlets 14, 15 can eventually lead to some pitting of the metal surface, even though the profile plates are made from stainless steel.

As above indicated, this cavitation energy is sufficicntly great that if typical magnetic oxide-coated polyethylene terephthalate glycol tape is placed between the upper and lower assemblies 10, 11 in an operating position, and the tape is left stationary, the magnetic coating itself will be removed within one minute or less. It is of interest to observe that with conventional high energy sonic cleaning devices such a magnetic tape coating may not be removed until after some 30 minutes of exposure to the ultrasonic-induced cavitation. This indicates the very high energies which are efficiently produced by the present device and at less cost than the old ultrasonic cleaning devices.

In addition to cleaning magnetic tapes and like flexible strip materials such as photostatic film, etc., the present invention may also be utilized to clean extruded metal strips of irregular cross section. In such a case, the cross seotion of the outlets of chamber 12 are fabricated to conform to the cross section of the extruded strip, so that the Bernoulli effect, and the cavitation phenomenon, will occur at all surfaces of the extrusion. The spacing of the outlets will be adjusted with due compensation for the cross sectional volume of the extrusion. When so cleaning metal extrusion, which are reasonably rigid, practice of the present invention may be achieved by providing means to move the cleaning device 8 along the stationary extrusion strip, if desired, rather than moving the strip through the cleaner.

While the cleaning device as shown in FIGURES l-S has substantially parallel side walls 22, 22', it will be understood that this is for convenience of construction rather than a critical feature of the design. It is equally within the scope of this invention to provide devices of the character described in which the chamber 12 would be somewhat diamond shaped in horizontal section as :well as in vertical section. Such a construction, as would be provided by a tapering of the side walls 22., 22' toward the outlets 14, 15, would in fact increase the pressure change resulting from the increased change of liquid velocity flow therethrough, for a given pumping volume. Similarly, it is not necessary that the profile plates be flat, as shown, over their entire surface, although it is desirable that at spacing St), the plate be substantially equally spaced from the strip material at all points as shown in FIGURE 5. This will insure the proper cleaning over the entire surface of the material.

It is also advantageous to provide for adjustment of deflector plates 46, 48, by forming a slightly elongated slot for receiving the mounting screws 94. This will permit adjustment of the gaps 95, 98 so that there will be adequate passageways for the tape without damaging the same, and to insure proper liquid flow around and over the deflector plates.

Other modifications and changes in the construction of the device as shown will be immediately suggested to those skilled in the art from the foregoing description, and it will be understood that the present invention is not limited to the making and use of cleaning devices of the character exactly as shown in the drawings, but rather by the spirit and scope of the following claims.

I claim:

1. A process for treating strip material by cavitation of a liquid which comprises:

flowing liquid into a chamber and then out through an outlet of said chamber immersed in a reservoir of liquid, while maintaining the level of a reservoir of said liquid above said outlet; adjusting the flow Volume and pressure of said liquid in relation to the cross-sectional configuration of said outlet so that as said liquid flows through said outlet, there is induced a change of velocity of said liquid from a lower to a higher value and then again to a lower value, wherein the change in velocity causes a change in pressure sufliciently great to create a zone of cavitation of the liquid in the region of said outlet;

passing said strip material in said reservoir of liquid and along a path of travel through the said zone of cavitation; and

adjusting the speed of travel of said strip material through said outlet while said cavitation is taking place so that said strip material is exposed to said cavitation for a period sufficient to treat the same 'for removal of surface contaminants on said strip material as desired by said cavitation.

2. A process for treating strip material by cavitation of a liquid which comprises:

flowing liquid into a chamber and then out through two outlets of said chamber immersed in a reservoir of liquid, While maintaining the level of a reservoir of said liquid above said outlets;

adjusting the flow volume and pressure of said liquid in relation to the cross-sectional configuration of said outlets so that, as said liquid flows through said outlets, there is induced at each outlet a change of velocity of said liquid from a lower to a higher value and then again to a lower value, wherein the change in velocity causes a change in pressure sufliciently great to create a zone of cavitation of the liquid in the region of each of said outlets;

passing said strip material into said reservoir of liquid and along a path of travel through the said zone of cavitation, in a first of said outlets, then through said chamber, and thereafter through the zone of cavitation in the second of said outlets;

balancing said cross-sectional configurations to maintain approximately equal flow rates through said respective outlets so as to stabilize the position of said strip material while the same is passing through and to prevent physical contact thereof with the structure of said outlets; and

adjusting the speed of travel of said strip material through said outlets while said cavitation is taking place so that said strip material is exposed to said cavitation for a period sutlicient to treat the same for removal of surface contaminants on said strip material as desired by said cavitation.

3. A process for treating strip material wherein said strip material is passed through a zone of cavitation to remove surface contaminants therefrom which comprises:

flowing a liquid through a restricted orifice immersed in a reservoir of liquid, said orifice having a configuration whereby a change in the velocity of said liquid is induced from a low to a high and again to a low value;

passing said strip material through said orifice;

causing liquid flow on all sides of said strip material in said orifice while maintaining the flow rate of said liquid at a volume and pressure sufiiciently great in relation to said configuration to cause said changes in the liquid velocity to create a zone of cavitation in said orifice; and

maintaining the liquid level of said reservoir above said 4. A process for cleaning strip material by cavitation of a liquid which comprises:

flowing said liquid through two regions while inducing a change in velocity of said liquid in each of said regions sufficiently great to cause a zone of cavitation in each of said regions, passing said strip material through one of said zones cocurrently with the flow of the liquid therein and passing said strip material through the other of said zones countercurrently with the flow of the liquid therein, while said cavitation is taking place. 5. The process of claim 4 wherein said liquid is an aqueous medium.

6. The process of claim 4 wherein said strip magnetic tape. 1

7. A process for cleaning strip material by cavitation of a liquid which comprises:

introducing said liquid into a chamber having constricted outlets, forcing said liquid out of said chamber through said outlets at a velocity sufiiciently high to cause cavitation in a zone of said outlets, passing said strip material through the zone in a first one of said outlets counter-currently to the liquid flow therein, and then passing the strip material through the zone of a second of said outlets cocurrently with the liquid flow therein, while said cavitation is taking place. 8. Apparatus for cleaning strip material by cavitation of a liquid which comprises:

means maintaining a reservoir of liquid; means defining a chamber having an inlet and an outlet immersed in and below the level of the liquid in said reservoir; means for passing strip material through said outlet; means gradually decreasing the cross-sectional area of said outlet from the central cross-sectional area of said chamber to a predetermined minimum, and then gradually increasing said cross-sectional area of said outlet; means for pumping liquid through said inlet into said chamber and then out through said outlet at a fiow rate sufiiciently great in relation to the dimensions of said outlet that the resulting change in velocity of the liquid as it passes through the region of said predetermined minimum cross-sectional area of said outlet causes cavitation of said liquid at said outlet and about said strip material passing through said outlet. 9. Apparatus for cleaning strip material by cavitation of a liquid which comprises:

means for maintaining a reservoir of liquid; means defining a chamber having a pair of liquid inlets; first and second outlet means; means for passing strip material along a path of travel through said outlet; means adjustably defining the orifice configuration of said outlets; said last-mentioned means including wall means having a region of minimum separation, establishing a region of predetermined minimum cross-sectional area of said outlet, and spaced increasingly further apart On either side of said region of said outlets; means for pumping liquid through said inlets into said chamber and then out through said outlets at a flow rate sufiiciently great in relation to the orifice configuration of said outlets that the resulting change in velocity of the liquid as it passes through the region of said predetermined minimum cross-sec tional area of said outlet causes cavitation of said liquid at said outlet and about said strip material passing through said outlet; and means for adjusting said orifice configurations so as to maintain balanced liquid flow on all said sides of said strip material while the same is passing through said outlets. 10. A device of the character described for the cleaning of strip material which comprises:

material is l means defining a chamber having a central portion,

means forming an at least partially constricted outlet at an end of said chamber, the cross sectional area of said central portion being substantially greater than the cross sectional area of said outlet, means maintaining a liquid reservoir containing said outlet at a liquid level above said outlet; means for introducing a cleaning liquid into said chamber at the central portion thereof and for continuously forcing said liquid from said chamber out through said outlet at a flow rate sufiiciently high in relation to the constriction of said outlet so that the resulting change in velocity of the flowing liquid as it passes through said outlet is suificiently great .to cause cavitation therein at said outlet and means for passing said strip material through said outlet while said cavitation is taking place. :11. A device of the character described for the cleaning of strip material which comprises:

side and top and bottom walls defining a chamber having a central portion, the ends of at least one of said walls being inclined to form constricted outlets at the ends of said chamber, the cross sectional area of said central portion being substantially greater than the cross sectional area of said outlets, means providing a reservoir and maintaining the liquid level therein above each of said outlets, means for introducing a cleaning liquid into said chamber into the central pontion thereof and for continuously forcing said liquid from said chamber out through said outlets at a flow rate sufi'iciently gneat in relation to the said inclination of the said one of said walls that the resulting change in velocity of the liquid flowing therethrough is sufficiently great to cause cavitation at said outlets, and means for passing said strip material through said outlets while said cavitation is taking place. 12. A device of the character described for the cleaning of strip material which comprises:

side and top and bottom walls defining a chamber having \a central portion, the ends of at least one of said walls being inclined to form constricted outlets at the ends of said chamber, the cross sectional area of said central portion being substantially greater than the cross sectional area of said outlets, means for introducing a cleaning liquid into said chamber at the central portion thereof and for continuously forcing said liquid from said chamber out through said outlets and means for passing said strip material through said outlets while said cavitation is taking place, in a direction first counter-current to the liquid flow through the first of said outlets, and then in a direction cocurrent with the liquid flow in the second of said outlets. 13. A device of the character described for cleanin stnip material which comprises:

a tank containing a cleaning liquid; a chamber forming means arranged in said tank; said chamber forming means including an upper assembly and a lower assembly adapted to be placed in mating relationship with each other;

10 said upper and lower assembly respectively comprising side walls and profile plates bounding said chamber 7 when said assemblies are placed in said mating relationship, and to form a central portion therein and outlets for said chamber; corresponding opposed profile plates in said upper and lower assemblies cooperatively inclining towards each other generally from a central portion of the chamber to one of said outlets;

means for adjustably spacing said opposed profile plates slightly apart from each other to form an orifice at said outlets and a flaring portion on each of said profile plates enlarging the space therebetween externally of said orifice;

means for passing said strip material through said chamber along a path successively through one of said outlets, said centnal portion and then a second of said outlets; liquid supply means for supplying said liquid to said central portion of said chamber and forcing the liquid therefrom through said outlets at a velocity sufficiently high to induce cavitation therein; 1

and means for maintaining the liquid level in said tank at a height above the said chamber.

14. A device according to claim 13 wherein said liquid supply means includes means for supplying liquid to said central portion in substantially equal amounts through said upper assembly and through said lower assembly.

15. A device according to claim 13 including guide means for guiding the passage of the strip material through said chamber comprising a first pair of fixed guides and a second pair of vertically movable guides arranged to raise and lower said flexible strip material to place the same in cleaning position on said lower assembly while said upper assembly is pivoted away from said vertical plane of the path of said strip material, and means for raising and lowering said second pair of guides.

16. A device according to claim 13 including means for reciprocally pivoting said upper assembly upwardly and outwardly away from the vertical plane of said path of said strip material through said chamber, to permit placing of said strip material in the said path, and for locking said assemblies in liquid tight mating relationship.

17. A device according to claim 16 having an upper conduit for supplying said liquid to said upper assembly and means for releaseaoly scaling said upper conduit to a liquid supply fixture in the wall of the tank.

18. A device according to claim 13 including means for deflecting at least a substantial portion of the liquid flow from said outlets and for causing said liquid to then flow in a direction opposed to the direction of flow through said outlets.

References Cited in the file of this patent UNITED STATES PATENTS 1,918,207 Grobstein July 11, 1933 2,194,565 Moss Mar. 26, 1940 2,289,753 Capstafi July 14, 194-2 2,536,208 Nystrom Jan. 2, 1951 2,647,846 Bagno Aug. 4, 1953 2,713,011 Durst July 12, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 108,025 October 22, 1963 Robert P. Gutterman It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 4, line 36, strike out "94a, 96a; line 48, for "22a" read 22'a Signed and sealed this 28th day of April 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

4. A PROCESS FOR CLEANING STRIP MATERIAL BY CAVIATION OF A LIQUID WHICH COMPRISES: FLOWING SAID LIQUID THROUGH TWO REGIONS WHILE INDUCING A CHANGE IN VELOCITY OF SAID LIQUID IN EACH OF SAID REGIONS SUFFCIENTLY GREAT TO CAUSE A ZONE OF CAVITATION IN EACH OF SAID REGIONS, 